A barbell is a piece of exercise equipment used in weight training, bodybuilding, weightlifting, powerlifting and strongman, consisting of a long bar, usually with weights attached at each end.

Barbells range in length from 1.2 metres (4 ft) to above 2.4 metres (8 ft), although bars longer than 2.2 metres (7.2 ft) are used primarily by powerlifters and are not commonplace. The central portion of the bar varies in diameter from 25 millimetres (0.98 in) to 50 millimetres (1.96 in) (e.g., Apollon's Axle), and is often engraved with a knurled crosshatch pattern to help lifters maintain a solid grip. Weight plates slide onto the outer portions of the bar to increase or decrease the desired total weight. Collars are used to prevent plates from moving outward unevenly so that the lifter does not experience uneven force.

The barbell is the longer version of the dumbbell that is used for free weight training and competitive sports, such as powerlifting, Olympic weight lifting, and CrossFit. Many exercises can be done using the barbell, such as bicep curl, bench press, Olympic weightlifting, overhead press, deadlift, and squat. Olympic barbells are usually an estimated weight of 20 kilograms (44 lb). Many fitness categories use the barbell for different reasons. For example, powerlifters use the barbell to perform compound exercise movements.